Research on Reasonable Drilling Parameters of Hydraulic Reaming in Soft and Thick Coal Seam and Its Application in Field

Abstract

In view of the fact that the outburst disaster of the soft 3# coal seam in the Sangshuping Coal Mine is mainly caused by in-situ stress, it is proposed to use hydraulic reaming, pressure relief and anti-reflection technology to remove some of the high geostress in the coal seam and improve gas drainage efficiency. Numerical simulation software was used to analyze the distribution of plastic failure and stress distribution of the coal body after reaming under the three-hole spacings of 4m, 6m, and 8m. The results show that the radius of the plastic failure zone around the borehole is about 2.2m when the rate of expanded coal chips is 3%; the width of the pressure relief area of a single reamed hole is about 3.2m. When the drilling hole spacing is 6m, it has a good pressure relief effect and reasonable amount of drilling work. After the reaming, the drainage concentration and flow rate are both improved. After reaming, the extraction concentration and flow rate have been improved. The hydraulic reaming technology can effectively solve the problem of outburst prevention in the thick seam of soft outburst dominated by ground stress in Sangshuping Coal Mine.